Knowledge concerning the electronic properties of defects is crucial for the understanding of the behaviour of these defects in semiconductors. Considering the important role defects play in most currently used devices it is not surprising that a great number of different measurement techniques have been developed with the aim of not only quantitatively determining the electronic parameters but also of identifying the defect chemically and evaluating the local environment of such defects. In most cases this goal can not be achieved by applying only a single (defect property) measuring technique.
In this paper an attempt is made, using two different examples, to show what achievements in defect characterization and identification can be obtained by combining two or more different measurement techniques. The first example is a single substitutional impurity, sulfur in silicon, while the second example deals with a more complex defect, the oxygen-vacancy center in silicon. In both cases a number of techniques such as different junction space charge measurements, Hall effect, absorption, ESR, photo-ESR, ENDOR photoconductivity, irradiation and annealing processes, and even theory were used to study the defect. The advantages and limitations of various methodologies will be discussed.